Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Passive Reflection Codebook Design for IRS-Integrated Access Point

Yuwei Huang, Lipeng Zhu, Rui Zhang

TL;DR

This paper tackles reducing pilot overhead in IRS-embedded AP systems by proposing a compact, offline codebook of IRS reflection patterns designed via azimuth-sector division. Each sector’s codeword is optimized to maximize the sector-min-average-effective-channel-power over LoS paths using alternating optimization and semidefinite relaxation, enabling slow adaptation to channel variations. The resulting codebook-based approach yields significant performance gains over benchmarks in both single-user and multi-user scenarios, while also reducing channel training overhead. The work demonstrates practical benefits for IRS-integrated AP deployments and outlines directions for extending to imperfections, wideband, MIMO, and multi-hop scenarios.

Abstract

Intelligent reflecting surface (IRS) has emerged as a promising technique to extend the wireless signal coverage of access point (AP) and improve the communication performance cost-effectively. In order to reduce the path-loss of the cascaded user-IRS-AP channels, the IRS-integrated AP architecture has been proposed to deploy the IRSs and the antenna array of the AP within the same antenna radome. To reduce the pilot overhead for estimating all IRS-involved channels, in this paper, we propose a novel codebook-based IRS reflection design for the IRS-integrated AP to enhance the coverage performance in a given area. In particular, the codebook consisting of a small number of codewords is designed offline by employing an efficient sector division strategy based on the azimuth angle. To ensure the performance of each sector, we optimize its corresponding codeword for IRS reflection pattern to maximize the sector-min-average-effective-channel-power (SMAECP) by applying the alternating optimization (AO) and semidefinite relaxation (SDR) methods. With the designed codebook, the AP performs the IRS reflection training by sequentially applying all codewords and selects the one achieving the best communication performance for data transmission. Numerical results show that our proposed codebook design can enhance the average channel power of the whole coverage area, as compared to the system without IRS. Moreover, our proposed codebook-based IRS reflection design is shown to achieve significant performance gain over other benchmark schemes in both single-user and multi-user transmissions.

Passive Reflection Codebook Design for IRS-Integrated Access Point

TL;DR

This paper tackles reducing pilot overhead in IRS-embedded AP systems by proposing a compact, offline codebook of IRS reflection patterns designed via azimuth-sector division. Each sector’s codeword is optimized to maximize the sector-min-average-effective-channel-power over LoS paths using alternating optimization and semidefinite relaxation, enabling slow adaptation to channel variations. The resulting codebook-based approach yields significant performance gains over benchmarks in both single-user and multi-user scenarios, while also reducing channel training overhead. The work demonstrates practical benefits for IRS-integrated AP deployments and outlines directions for extending to imperfections, wideband, MIMO, and multi-hop scenarios.

Abstract

Intelligent reflecting surface (IRS) has emerged as a promising technique to extend the wireless signal coverage of access point (AP) and improve the communication performance cost-effectively. In order to reduce the path-loss of the cascaded user-IRS-AP channels, the IRS-integrated AP architecture has been proposed to deploy the IRSs and the antenna array of the AP within the same antenna radome. To reduce the pilot overhead for estimating all IRS-involved channels, in this paper, we propose a novel codebook-based IRS reflection design for the IRS-integrated AP to enhance the coverage performance in a given area. In particular, the codebook consisting of a small number of codewords is designed offline by employing an efficient sector division strategy based on the azimuth angle. To ensure the performance of each sector, we optimize its corresponding codeword for IRS reflection pattern to maximize the sector-min-average-effective-channel-power (SMAECP) by applying the alternating optimization (AO) and semidefinite relaxation (SDR) methods. With the designed codebook, the AP performs the IRS reflection training by sequentially applying all codewords and selects the one achieving the best communication performance for data transmission. Numerical results show that our proposed codebook design can enhance the average channel power of the whole coverage area, as compared to the system without IRS. Moreover, our proposed codebook-based IRS reflection design is shown to achieve significant performance gain over other benchmark schemes in both single-user and multi-user transmissions.
Paper Structure (15 sections, 16 equations, 13 figures, 1 table, 1 algorithm)

This paper contains 15 sections, 16 equations, 13 figures, 1 table, 1 algorithm.

Table of Contents

  1. Introduction
  2. IRS-Integrated AP: System and Channel Models
  3. System Model
  4. Channel Model
  5. Reflection Codebook Design Based on Sector Division
  6. Proposed Solution to (P1.$D$.$d$)
  7. Numerical Results
  8. Performance Evaluation of Codebook Design
  9. Performance Evaluation for Single-User Transmission
  10. Effect of Channel Estimation Overhead
  11. Effect of Codebook Size
  12. Effect of Rician Factor
  13. Slow Adaptation for IRS Passive Reflection
  14. Performance Evaluation for Multi-User Transmission
  15. Conclusions

Figures (13)

  • Figure 1: System model and architecture of the IRS-integrated AP.
  • Figure 2: Examples for codebook design based on sector division for single-user transmission (top-view).
  • Figure 3: Elevation power pattern of the designed codeword $\hbox{\boldmath{$\Theta$}}_{4,1}^{*}$.
  • Figure 4: Azimuth power pattern of the designed codeword $\hbox{\boldmath{$\Theta$}}_{4,1}^{*}$.
  • Figure 5: Average SMAECP versus the number of sectors $D$.
  • ...and 8 more figures

Theorems & Definitions (1)

  • Remark 2.1